Films of metals and metal oxides, particularly ruthenium films and oxides thereof, are becoming important for a variety of electronic and electrochemical applications. For example, high quality RuO.sub.2 thin films deposited on silicon wafers have recently gained interest for use in ferroelectric memories. Ruthenium films are generally unreactive to silicon and metal oxides, resistant to diffusion of oxygen and silicon, and are good conductors. Oxides of ruthenium also possess these properties, although perhaps to a different extent.
Thus, films of ruthenium and oxides thereof have suitable properties for a variety of uses in integrated circuits. For example, they can be used in integrated circuits for electrical contacts. They are particularly suitable for use as barrier layers between the dielectric material and the silicon substrate in memory devices, such as ferroelectric memories. Furthermore, they may even be suitable as the plate (i.e., electrode) itself in capacitors.
There are a wide variety of ruthenium compounds that can be used as precursors for the preparation of such films. Many are particularly well suited for use in chemical vapor deposition techniques. See, for example, U.S. Pat. No. 5,372,849 (McCormick et al.), which discloses the use of ruthenium compounds containing carbonyl ligands and other ligands. However, such compounds typically form dimers, which are less volatile and not as easily used in chemical vapor deposition techniques. Thus, there is a continuing need for methods for the preparation of ruthenium metal films using chemical vapor deposition techniques.